Acoustical panel coating and process of applying same

ABSTRACT

A coating composition and process of applying the coating to a substrate are provided herein. The coating composition includes filler particles, binder and a liquid carrier, such as water. The filler particles have an average particle size in the range from about 100 to about 600 microns and preferably in the range from about 200 to about 450 microns. The coating composition comprises from about 15% to about 50% by weight liquid carrier and from about 35% to about 90% by dry solids weight filler particles. The coating composition preserves the acoustic performance characteristics of the substrate to which it is applied, while imparting a textured appearance to the substrate, making the substrate virtually indistinguishable from surrounding panels.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.provisional application Ser. No. 60/414,950, filed Sep. 30, 2002.

BACKGROUND

The present invention relates generally to ceiling systems havingacoustical panels and more particularly to coatings for acoustic scrimsof flat panel sound radiators and acoustical panels and a method forapplying these coatings.

As the service sector of the economy grows, more and more workers findthemselves in offices rather than in manufacturing facilities. The needfor flexible, reconfigurable space has resulted in open plan workspaces,large rooms with reduced height, moveable partitions, and suspendedceiling systems. Workstation density also is increasing, with moreworkers occupying a given physical space. Additionally, speakerphones,conferencing technologies, and multimedia computers with large soundreflecting screens and voice input tend to increase the noise level ofthe workplace.

In response to increased noise within the workplace, suspended ceilingshaving acoustical ceiling panels have been developed to absorb and abateextraneous noise within a confined space. The modular design of suchpanels allows for ease of installation and ease in office spacereconfiguration. Building planners often specify modular acousticalpanels as a standard system within their designs. Acoustical panels canboth enhance the work environment by providing acoustic sound absorptionand attenuation and by providing a pleasant monolithic visualappearance. Thus, there has been an increased emphasis on specifyingsuspended ceiling systems with high acoustic absorptions and pleasantvisual appearances.

Building planners prefer to utilize ceiling systems that aresubstantially monolithic in structure and design. Such ceiling systemsprovide a pleasant visual appearance to persons viewing the ceiling frombelow. Loudspeakers often are required in office spaces where ceilingsare formed of acoustical panels in a suspended ceiling grid.Loudspeakers are used to provide sound in a workspace such as pagingmessages, music, and background masking sounds. The background maskingsounds reduce the effect of unwanted noise from infrastructure systemssuch as ventilation systems and which mask speech noise allowing forgreater speech privacy. Unfortunately, many loudspeaker systems do notintegrate visually into the ceiling system and, as a result, interruptthe desired monolithic appearance of the ceiling.

By way of example, many speaker systems, when installed, protrude belowthe plane of the acoustical panels, thus interrupting the planar surfaceof ceiling. Some speaker systems can be installed by cutting a hole in aacoustical panel and installing a speaker with a round perforated grillwithin the opening. Such a speaker grill, while effective, neverthelessinterrupts the monolithic appearance of the ceiling and is consideredunsightly by some.

More recently, flat panel sound radiators are being utilized in place ofthese traditional loudspeakers. The flat panel radiators are morevisually pleasing than traditional loudspeakers because they areco-extensive with the plane of the ceiling and have the size and look ofceiling panels. However, existing flat panel sound radiators generallyare detectable because the coloring and texture of the facing does notmatch precisely the surrounding ceiling tiles. Thus, these flat panelradiators still are considered by some to present an unacceptableappearance.

Attempts have been made to develop coatings to be applied to the facingsof flat panel sound radiators so as to render the facings similar inappearance and texture to surrounding acoustical panels. However, it hasproven difficult to formulate a coating and a process for itsapplication which provides the facing material with the properappearance and texture while continuing to provide the desired acoustictransparency. These requirements heretofore have seemed to be somewhatmutually exclusive conditions.

SUMMARY

The present invention provides a coating composition which, when appliedto a substrate, such as an acoustical panel, scrim or facing of a flatpanel sound radiator, preserves the acoustical performancecharacteristics of the substrate and imparts a textured appearance tothe substrate making it visually indistinguishable from surroundingpanels in a wall or suspended ceiling system. Thus, a monolithicappearance in the wall or ceiling system is achieved.

Briefly described, the coating composition comprises filler particles, abinder and a liquid carrier, such as water. The filler particles have anaverage particle size in the range from about 100 to about 600 micronsand preferably in the range from about 200 to about 450 microns. Thecoating composition comprises from about 15% to about 50% by weightliquid carrier and from about 35% to about 90% by dry solids weightfiller particles.

The present invention also provides a method for applying a coatingcomposition to a substrate. The method includes providing a coatingcomposition containing filler particles, a binder and a liquid carrier;applying the coating composition to a substrate using a high volume, lowpressure (HVLP) spray apparatus; and drying the coated substrate. Theresulting coated substrate has an airflow resistance in the range fromabout 600 mks rayls to 900 mks rayls and a texture value in the rangefrom about 20 ml/sq ft to about 65 ml/sq ft.

The present invention also is directed to a coated scrim that exhibitsan airflow resistance value of about 900 mks rayls or less and a texturevalue of about 20 ml/sq ft or greater. The coated scrim also has ahiding power value of at least 98%. The coated scrim may be used inconjunction with acoustical panels, flat panel sound radiators, walls,furniture, cubicle partitions, HVAC systems or other structures in whichacoustical transparency and a textured appearance is desired. The coatedscrim includes a woven or non-woven porous material such as non-wovenfiberglass, and the coating composition of the invention.

An acoustical panel exhibiting a textured appearance also is encompassedby the present invention. The acoustical panel includes a substrate,such as wood and mineral fiberboard, and the coating composition of theinvention. The substrate has a backing surface and a facing surfacewhich is substantially free of punch holes, wheel abrasions, embossingand erosion. The acoustical ceiling panel of the invention exhibits anNRC value of about 0.5 or greater and a texture value of about 20 ml/sqft or greater. In an alternative embodiment, the acoustical panel can becomposed of a substrate and the aforementioned coated scrim.

The present invention further provides a suspended ceiling system havinga grid, a plurality of acoustical panels and at least one coated scrim,the plurality of acoustical panels and the at least one coated scrim aresupported by the grid. The coated scrim and the plurality of acousticalpanels exhibit a similar surface texture which provides a monolithicappearance for the system. The suspended ceiling system may furtherinclude a flat panel sound radiator positioned above the coated scrim.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. is a cross-sectional view of a coated scrim in accordance withan exemplary embodiment of the invention.

FIG. 2 is a cross-sectional view of a coated acoustical panel inaccordance with an exemplary embodiment of the invention.

FIG. 3 is a cross-sectional view of a coated acoustical panel, whereinthe coated scrim of FIG. 1 is applied to the acoustical panel.

FIG. 4 is a perspective view of a suspended ceiling system whichincludes the coated scrim of FIG. 1.

DETAILED DESCRIPTION

The present invention is described in further detail below and is shownin the accompanying drawings wherein like numerals refer to like partsthroughout the several views.

The coating composition of the invention includes filler particles, abinder and a liquid carrier. The filler particles are of sufficient sizeto impart a textured appearance to a substrate, while tending not tocompletely plug or seal the openings within the substrate. The fillerparticles have an average particle size in the range from about 100 toabout 600 microns and preferably in the range from about 200 to about450 microns. The filler particles constitute from about 35% to about 90%by weight of the coating composition on a dry solids basis and arepreferably formed of calcium carbonate, dolomite, dolomitic limestone orcombinations thereof. The calcium carbonate particles have an averageparticle size of approximately 450 microns and may be screened through a30 mesh sieve. One example of a suitable calcium carbonate fillermaterial is Geotex's TXS, produced by Huber Engineering Materials. Thedolomite particles generally exhibit an average particle size ofapproximately 260 microns. One example of suitable dolomite is DF3015from Specialty Minerals, Inc.

The binders are selected from natural polymers, modified naturalpolymers, synthetic polymers and combinations thereof. The syntheticpolymers are formed from the following monomers: vinyl acetate, vinylpropionate, vinyl butyrate, ethylene, vinyl chloride, vinylidinechloride, vinyl fluoride, vinylidine fluoride, ethyl acrylate, methylacrylate, propyl acrylate, butyl acrylate, ethyl methacrylate, methylmethacrylate, butyl methacrylate, hydroxyethyl methacrylate, styrene,butadiene, urethane, epoxy, melamine, ester, and combinations thereof.The natural and modified natural polymers are selected from proteins andcarbohydrate polymers, such as starch. Where pigment is included in thecoating composition, the binder concentration is such that the pigmentto binder ratio is in the range from about 5:1 to about 30:1 on a drysolids basis.

The liquid carrier content of the coating composition may be varied soas to result in the concentration of the solids portion being in therange from about 50% to about 85% by weight of the coating composition.Consequently, the liquid carrier content can be in the range from about15% to about 50% by weight of the coating composition. In oneembodiment, the coating composition has a solids concentration in therange from about 70% to about 80% by weight.

The coating composition of the invention generally exhibits a viscosityin the range of about 1100 to about 5000 cps as measured on a Brookfieldviscometer at 10 rpm. In one embodiment, the viscosity of the coatingcomposition is such that the suspension is stable and the coatingcomposition exhibits minimal spread when applied to a substrate, such asa scrim or panel.

In addition to fillers, binders and a liquid carrier, the coating mayinclude secondary particles, dispersants, defoamers and thickeningagents which impart color, gloss, durability and other desiredproperties to the coated surface. Generally, the secondary particleshave an average particle size in the range from about 0.1 to about 30microns and can constitute from about 5% to about 55% on a dry solidsbasis of the coating composition. The secondary particles are selectedfrom titanium dioxide, barium sulfate, clay, mica, dolomite, silica,talc, perlite, gypsum, wollastonite, calcite, aluminum trihydrate, zincoxide, zinc sulfate, polymers, pigments and combinations thereof. In oneexample embodiment, the filler particles and secondary particles used inthe coating composition are selected from limestone, dolomite, silicaand mixtures thereof. In another example embodiment, the coatingcomposition contains filler particles and secondary particles selectedfrom calcium carbonate, titanium dioxide, clay and mixtures thereof.

Additionally, tetrasodium pyrophosphate, such as that available fromAshland Chemical Company, may be used as a dispersing agent. Also, a 30%solution of hydroxyethyl cellulose may be used as a thickener. Anexample of hydroxyethyl cellulose is Natrosol FPS-HB from HerculesIncorporated.

The coating composition of the present invention can be applied to asubstrate using an HVLP (high volume, low pressure) apparatus to providethe desired textured visual appearance and acoustical characteristics tothe substrate. The sprayed dispersion pattern of the coating compositionusing an HVLP spray gun provides the separation necessary to coat thesubstrate, while not completely clogging the pores within the substrate.Clogging or sealing of the pores of the substrate tends to prevent orreduce significantly the acoustical transparency that is necessary in anacoustical panel or a flat panel sound radiator.

Generally, the coating composition is fed into a pressure tank that isin flow communication with an HVLP spray gun. For example, the pressuretank can be a one-gallon tank supplied by Binks and the HVLP spray gunmay be a model Mach 1 SL or Mach 1A from Binks with a 909VT fluid tipand a 905P air tip attached thereto. The fluid tip or fluid nozzle usedwith the HVLP spray gun has an opening that is sufficiently large toallow the filler particles to pass therethrough without clogging thenozzle or spray gun. The coating is atomized by the spray gun andapplied under pressure to the substrate. The HVLP spray gun provides alower exit velocity to the coating composition than generally isprovided by other air atomizing application methods, thereby minimizingbounce-back of the coating from the substrate and tending to generatelarger droplets distributed in a more narrowly defined pattern. The HVLPspray apparatus tends to generate a discontinuous finish that exhibits acoarse texture and preserves the desired acoustical characteristics ofthe substrate.

The coating composition can be applied with the HVLP spray gun to asubstrate to form a single coat or layer that is then allowed to dry oris dried under heated conditions. Additional coats or layers of thecoating composition can be applied on top of the first coat with adrying step conducted between each application step. A finish coatingmay be applied over the coating layers containing the larger fillermaterial. Other process steps such as filtering, transfer, drying andhandling can be conducted as desired. Also, other features may beincluded in the application process of the present invention, such asthe use of diaphragm pumps, piston pumps, automated paint booths withreciprocating or stationary guns, to provide a coating on a surface.

Variations of the components within the coating composition within theranges described above, as well as variations in the pressures, flowrates, application rates and nozzle types of the HVLP spray apparatus,can provide variations in the textured appearance of the coatedsubstrate. For example, the coating composition when applied to asubstrate can exhibit an appearance that is substantially equivalent tothe Dune product line offered by Armstrong World Industries. Otherfinishes, such as that of the Cirrus product line of Armstrong WorldIndustries, Inc, also can be generated by application of the coating ofthe present invention.

In addition to exhibiting a desired textured appearance, a substrate,when coated with the coating composition of the invention exhibitsdesired performance characteristics, such as airflow resistance andhiding power. Airflow resistance is typically determined by the ASTMC522-87 test method. For example, a substrate, such as a scrim, coatedwith the coating composition of the present invention according to theprocess described herein, can exhibit an airflow resistance of 900 mksrayls or less. In one embodiment, the airflow resistance is in the rangefrom about 600 mks rayls to about 900 mks rayls. A coated scrimexhibiting this level of airflow resistance will allow sound to passthrough the material at a rate acceptable for using the material as anacoustical facing for a flat panel sound radiator.

As shown in FIG. 1, a scrim 16 can be coated with the coatingcomposition 18 of the invention using the HVLP process described herein.The scrim 16 can be formed of woven or non-woven fibers. For example,the scrim 16 can be fiberglass, such as A80EF or YK111 supplied byOwens-Corning. The scrim 16 can also be made of cellulose,polypropylene, polyethylene, glass, polyester, polyamide, and mixturesthereof. An uncoated scrim 16 generally exhibits an airflow resistancevalue of less than 600 mks rayls, as well as a texture value of 11 ml/sqft. In contrast, a coated scrim 14 exhibits an airflow resistance valueof 900 mks rayls or less and a texture value of about 20 ml/sq ft orgreater. In one embodiment, the coated scrim 14 exhibits an airflowresistance in the range from about 600 to 900 mks rayls and a texturevalue in the range from about 20 ml/sq ft to about 65 ml/sq ft. Thetexture value can be quantitatively measured using a Texture Volume Testin which the topographic features of the textured are filled and thevolume of the material required to fill the spaces between the featuresis measured as discussed in the examples below.

Generally, the acoustical performance properties of an acoustical panelformed of a porous material, such as mineral fiber, are enhanced bypunching holes, wheel abrading, embossing or eroding the facing surfaceof the board. The typical desired NRC value for a acoustical panel isabout 0.50. This is a standard test method in accordance to ASTM Testdesignation C 423-84a, whereby sound adsorption is measured at variousfrequencies. However, since conventional coatings are generally notsufficiently acoustically transparent when applied to panel having athickness of about 0.75 inches or less, one or more of these performanceenhancing features must be applied to the panel. Without theseperformance enhancing features, conventional coated acoustical panels ofthis thickness generally cannot attain the desired acousticalperformance characteristics.

By applying the coating composition 18 of the invention directly to asubstrate 22 as shown in FIG. 2 or by combining the coated scrim 14 ofFIG. 1 with a substrate 22, as shown in FIG. 3, a panel can be formedwhich has the desired textured appearance and the acoustical performanceproperties which allow the panel to absorb a desired amount of ambientnoise or sound even when the board has a thickness of about 0.75 inchesor less. The substrate 22 can be substantially free of punch holes,wheel abrasions, embossing and erosion. As used herein, the phrasesubstantially free of punch holes, wheel abrasions, embossing anderosion describes an acoustical panel that has none of these features orhas these features in an amount insufficient to beneficially affect theacoustical performance of the acoustical panel. The substrate 22 has athickness of up to about 0.75 inches. The panel is made of fibersselected from wood, mineral, glass and mixtures thereof and can becoated with a coating composition 18 as described above. Even when thesubstrate 22 is substantially free of punch holes, wheel abrasions,embossing and erosion, the coated acoustical panel exhibits an NRC value0.50 or greater, and preferably about 0.65 or greater, and a texturevalue of 20 ml/sq ft or greater, and preferably 35 ml/sq ft or greater.

The coated scrim 14, can also be used to hide HVAC system components ina suspended ceiling system or serve as the facing of a flat panel soundradiator, such as the flat panel sound radiator described in U.S. Pat.No. 6,386,315, which is hereby incorporated by reference as if fully setforth herein. The coated scrim provides the necessary airflow resistanceto allow sound generated by the radiating panel of the flat panel soundradiator to pass through the scrim into the surrounding space. Anairflow resistance of 900 mks rayls or less is sufficient to allow soundgenerated by the sound radiator to enter the surrounding space withoutadverse effects on the sound quality. In addition, the scrim providesthe flat panel sound radiator with the desired textured appearance sothat the radiator does not interrupt the monolithic appearance of thesuspended ceiling when combined with other acoustical panels within asuspended ceiling system.

As a result, a suspended ceiling system 10, as shown in FIG. 4, caninclude a plurality of acoustical panels 24 and at least one scrim 14.The panels can be panels which have been subjected to acousticalperformance enhancement processes, such as hole punching, wheelabrading, embossing and erosion or those similar to acoustical panel 22,shown in FIGS. 2 and 3, which have not been subject to such processes,but that, nevertheless, exhibit NRC ratings of 0.5 or greater when thecoating of the invention is applied to their facing surfaces. The coatedscrim 14 and the acoustical panels 24 may be coated with substantiallythe same coating composition, as that described above, or differentcoating compositions that, nonetheless, provide the same predeterminedtexture, resulting in a monolithic appearance for the suspended ceilingsystem 10. Each of the plurality of acoustical panels 24 and the coatedscrim 14 exhibit texture values that are within approximately 24 ml/sqft of each other, and preferably within approximately 10 ml/sq ft. Inone example embodiment, the acoustical panels 24 and the coated scrim 14exhibit texture values in a range of about 35 ml/sq ft to about 65 ml/sqft and are within 10 ml/sq ft of each other within this range.

The ingredients for the coatings in the following examples were mixedtogether to form each coating composition. The coatings were thenapplied to a panel or scrim surface. The following table shows exampleswhere different coating compositions and spray gun types were used. Theresulting acoustical performance and visual appearance of the coatedsubstrates is also provided. TABLE 1 Example 6 (1^(st) Coat/ 1 2 3 4 52^(nd) Coat) 7 Application  59  64.5  61.3  63.8  60   14/52.3  60 Rate(gm/sq ft) Formula Geotex TXS * 72.1% DF3015 59.3%  84.0%  12.0% 84.0% 84.0%  80.0%/66.7% 69.8% Tipure R960 9.3%  9.2% 9.3% 9.3% 13.3%/26.6%23.5% Hydrocarb 60 26.4%  SpaceRite S-3 7.4% Airflex 4530 6.4% 6.2% 6.2% 6.2% 6.2% 6.2%/6.2%  6.2% Additives ** 0.5% 0.5%  0.5% 0.5% 0.5%0.5%/0.5%  0.5% Solids 74% 74.6%  74.6% 74.6%  74.6%  74.7%/74.7% 74.7%Filler: Binder 14.6:1 15:1 15:1 15:1 15:1 15:1/15:1 15:1 Ratio Viscosity(cps) 1400 2700 3200 2700 2700 3700/2920 2300 Spray Gun Type Intern.Extern. HVLP HVLP HVLP HVLP HVLP Model  95  95 Mach1SL Mach1SL Mach1SLMach1SL Mach1SL Fluid Tip 59ASS 68SS 909VT 909VT 909VT 909VT 909VT AirTip  244 68BP 905P 905P 905P 905P 905P Atomization  30  20  25  20  1025/25  20 Pressure (psi) Airflow  985 1030  700  660  650  691  700resistance of Coated Substrate (mks rayls) Texture  33  48  61  48  47 44  47 (ml/sq ft) Visual Dune Dune Dune Dune Cirrus Dune DuneAppearance* screened through a 30 mesh sieve** dispersant, defoamer, thickener

Spacerite S-3 is an aluminum trihydrate that has an average particlesize of 1 micron and is available from Alcoa Industrial Chemicals.Hydrocarb 60 is a calcium carbonate product with an average particlesize of 2 microns from OMYA, Inc. Tipure R960 is a rutile titaniumdioxide product with an average particle size of 0.5 microns fromDupont. Geotex TXS is a calcium carbonate product from Huber screenedthrough a 30 mesh sieve and having an average particle size of 450microns. DF3015 is dolomitic limestone with an average particle size of260 microns from Specialty Minerals, Inc. Airflex 4530 is an ethylenevinyl chloride latex from Air Products.

In yet another example, the following ingredients were mixed using abench-top dispersing mixer to form a coating composition. Otheradditives, such as dispersants, defoamers, and biocides can be used withthis coating composition. TABLE 2 Trademark Percentage by WeightIngredient Name Company (as received basis) Water 19.96 Titanium DioxideTi-Pure R960 Dupont 17.72 Ethylene Vinyl Airflex 4530 Air Products 9.24Chloride Latex Limestone DF3015 Specialty 52.00 Minerals HydroxyethylNatrosol Aqualon 0.48 Cellulose FPS HB Misc. Additives 0.6The viscosity of the coating composition was 2300 cps at a solidscontent of 76.3% by weight of the total composition. The coating wasplaced into a 1 gallon Binks Pressure Tank connected to a Binks HVLPspray gun (Model Mach1SL, 909VT Fluid Tip, 905P air tip). The tankpressure was set to 5 psi and the atomization air pressure was set at 20psi. The coating was uniformly applied onto an Owens Corning YK111fiberglass scrim and then dried in a Hotpack oven at 300° F. for 5minutes. The finished scrim exhibited a airflow resistance of 700 mksrayls. The finished scrim was taped onto a metal frame and theninstalled in a ceiling surrounded by Armstrong World Industries, Inc.Dune acoustical panels. This finished scrim was substantially visuallyequivalent to the Armstrong World Industries, Inc. Dune acousticalpanels. The texture of the finished scrim was 47 ml/sq. ft. and thetexture of the Dune acoustical panels were 41. The finished scrimexhibited a hiding power value of 98.2%.Texture Volume Test:

Samples of coated and uncoated scrims and fiberboards were evaluated todetermine the quantitative texture values of each. Each sample was cutto 12″×12″. The scrim samples individually were taped to 12″×12″ flatboard. The samples individually were placed on a wooden frame made from1″×1″ hardwood with 2 holes drilled into each side to accommodate nailsto hold the sample in place. The frame measured 12 1/16″×12 1/16″ on itsinside dimensions. It is important that the sample fits tightly into theframe. The frame and the sample were flipped so that the sample face wasflush with the frame top. Nails were inserted into the holes to hold thesample in place. The frame and the sample were again flipped so that thesample was face up. Glass beads of 40-60 mesh (US Sieve) from PottersIndustries Inc., Potsdam, N.Y., were placed on the sample to form a thinlayer. The beads were spread using a straight edge to completely fillthe texture of the sample. The sample was tapped frequently to settlethe beads into the texture. A small brush was used to gently brush awayall beads from the edges of the frame. The beads were then transferredto a clean piece of paper by flipping the board and frame. The back ofthe board was gently tapped to remove all of the beads from the sample.A funnel was used to pour the beads into a graduated cylinder. Thecylinder was gently tapped to settle the beads. The volume of the beadswas recorded. The results of these tests were as follows: TABLE 3 Volumeof Beads Sample (ml/ft²) Uncoated scrim 11 Uncoated sanded mineralfiberboard (substrate) 15 Durabrite coated scrim 7 Dune mineralfiberboard (grit) 41 Cirrus-type mineral fiberboard (embossed) 44 Cirrusmineral fiberboard (eroded) 41 Dune coated scrim 40 Cirrus coated scrim37

Excluding fissuring and punching methods, the texture on the face ofceiling panels can range from coarse to very fine. In this test, verycoarse textures generally yield very large (>40 ml/sq ft) volumes, whilea very fine texture would yield a very low (<20 ml/sq ft/sq ft) volume.The Texture Volume Test can be used to quantify uniformly orsubstantially smooth textures. The term substantially smooth means thatthe surface substrate measured defines a plane and at least 50% of thesurface is substantially flush with the plane and is substantially freeof projections extending from the surface beyond the plane. If this testis not used on “substantially smooth” textured surfaces, e.g. when thetexture consists of a few scattered peaks, the test can produceinaccurate and overly large volume values. It should be noted thatalthough the Dune texture is fine and the Cirrus texture is coarse, thequantitative results are similar for the two textures since the openspaces around the textured peaks are measured. Thus, there are a smallnumber of large spaces in Cirrus texture and a large number of smallspaces in the Dune texture.

As shown in Table 3, the uncoated scrim, the uncoated sanded mineralfiberboard and the Durabrite coated scrim exhibit texture values thatare significantly less than the Dune and Cirrus coated scrims which aretextured using grit, embossing, or erosion techniques. However, thescrims coated with the coating of the present invention to produce Duneor Cirrus textured appearances exhibit texture values that arecomparable to the conventionally textured fiberboards. Thus, applicationof the coating composition of the present invention results in texturedvisuals that are virtually indistinguishable, both quantitatively andvisually, from conventionally textured panels. The coating compositioncan be applied directly to a fiberboard without a scrim to producesimilar texture value results.

Tests of mineral fiberboard coated with the coating composition of theinvention were also conducted. A prime coat was applied to the minerfiberboard before the textured coating was applied, in order to impart awhite color to the board. The NRC value of the prime coated mineralfiberboard was approximated 0.70. The coating composition of the presentinvention was then applied to the prime coated mineral fiberboard. Theresulting fiberboard exhibited an NRC rating of 0.65. The texture of thedouble coated mineral fiberboard was 39 ml/sq ft and was virtuallyindistinguishable from conventional Dune panels which have an NRC valueof approximately 0.30 and a texture value of approximately 41 ml/sq ft.

Hiding Power:

The hiding power was measured by placing the scrim on an Opacity TestChart, such as the Opacity Chart Form N2A from the Leneta Company. TheOpacity Chart includes both a white section and a black section overwhich the lightness of the scrim can be measured. Hiding power isdetermined by dividing the lightness value of the black section by thelightness value of the white section.

It will be understood by those of skill in the art that variations onthe embodiments set forth herein are possible and within the scope ofthe present invention. The embodiments set forth above and many otheradditions, deletions, and modifications may be made by those of skill inthe art without departing from the spirit and scope of the invention.

1-47. (canceled)
 48. A method of applying a coating to a substrate, themethod comprising the steps of: providing a coating composition havingfiller particles, binder and a liquid carrier; spraying the coatingcomposition from a high-volume, low pressure spray apparatus onto aporous substrate; and drying the coated substrate; the resulting coatedsubstrate having an airflow resistance value in a range from about 600mks rayls to 900 mks rayls and a texture value in a range from about 20ml/sq ft to about 65 ml/sq ft.
 49. The method of claim 48, whereinspraying occurs at an atomization pressure in a range from about 10 psito about 30 psi.
 50. The method of claim 48, wherein said coatedsubstrate exhibits a hiding power of about 98% or greater.
 51. Themethod of claim 48, wherein the filler particles have an averageparticle size in a range from about 100 microns to about 600 microns inan amount from about 35% to about 90% by weight on a dry solids basis.52. The method of claim 51, wherein the filler particles are selectedfrom the group consisting of calcium carbonate, dolomite andcombinations thereof.
 53. The method of claim 51, wherein the fillerparticles exhibit an average particle size in a range from about 200 toabout 450 microns.
 54. The method of claim 48, wherein the poroussubstrate is a mineral fiberboard.